The system updates the modification date automatically, but to see the modified date, you must add this field to the Folder HelpDesk homepage view. The images below are from Outlook 2013.
1. Go to View >View Settings.
2. Click on the Columns button.
3. Select “Date/Time fields” in the dropdown, select “Modified” and click on Add and then OK.
4. Now you will get a new field above the ticket list in Folder HelpDesk , and when you click it the tickets are arranged after modified date.
